The search for a driver that would duplicate the performance of this Mesa cab would be greatly aided by measured TS parameters and amplitude response (on & off axis). Without these or an unreal amount of luck, the only path forward is to discard the tone of the Mesa cab and start from scratch. As bass players, we always want loud and reliable, but preferences diverge considerably with respect to deep bass extension, prominence of deep fundamentals, punch, growl, articulation, HF extension, etc. If the Mesa cab is the OP's 'holy grail' of tone, and meets his spl needs, then, if he wants to gig with it, the weight needs to be reduced. This can be accomplished by either reducing the weight of the Mesa cab, or by building a modern, light weight cab for the drivers.
